Overload circuit-breaker.



BEST AVAILABLE COPY D. LARSON.

OVERLOAD CIRCUiT BREAKER.

APPLICATION FILED OCT. 14. 1911.

PatentedApr. 6, 1915.

5 mm wtbz,

v UNITED STATES DAV ID LARSON, or YONKERS, NEW YORK, ASSIGNOR T OTIS nLnva'goifoomrAnx, or

JERSEY our, NEW JERSEY,'A CORPORATION or nwennsmr.

PA ENT orF cE,

OVERLOAD CIRCUIT-BREAKER.

Patented Apr. 6, 1915.

Application filed October 14, 1911. Serial No. 654,651.

1,134,750. Specification of Letters Patent.

tailed description and high resistancewinding 15 'cores being connected ,to

' geth'er and To all whom it may concern:

Be it known that 1, DAVID ject of the King of Sweden, residing at a general description of the will now give a more deand point out the various electrical circuits associated therewith The main line switch comprises a sole-, noid i which when energized is adapted to raise a core 7, thereby closing the contacts 8 and 9. The contacts 8 control acircuit to the motor-while the contacts 9 control a circuit to the releasing solenoid of the brake 90. The overload relay 30 comprises one or more cores such as 17- I I-laving given various parts, I

and 16 rethe Lasso), a subthe contacts 18.

and 17 and a low closed contacts 18, a regulating screw 19 being prop dcd for the purpose of adjusting the core 1; with respect to its magnet windthe motor to run up to It will be observed that the armature circuit includes the low'resistance winding of the overloadrelay and the current in this vi'nding tends to By'mcans of the screw 19, however, the core 17 is so positioned with respect to the. winding 15 that, the core will not move upwardly except and until the current flowing to the motor becomes excessive 105 and the motor is overloaded. 'When an overload does take place the core 17 is raised and the contacts 18 become separated and the high resistance winding 16 is insertedin main line 110 series with the solenoid 6 of the Yonkers, in the county of \Vestehester and ing 15. The master switch 20 comprises a 5 State of New York, have invented a new and lever 11 adapted manually to be moved into 0 useful Improvement in Overload Circuitelectrical engagement with the contact strips Breakers, of wliich'the following is a speci- 1'2 13 and ll. 7 ficatiom i Q The operation of the apparatus just do My invention relates to protective devices scribed is as follows: Upon moving the lever for electrical apparatus, and has for its obof the master switch into a position 'indi 5 ject the provision of means for interrupting cated by the broken line a, the contact -the circuit of a translating device upon exstrips 12 and 13 are shortcircuited and a [cessive flow of current. circuit, is closed to the winding 6 of the A further object of my invention is the main line switch 10, this circuit being traced 5pr0vision of a simple, practical and eilicient fromthe line to the contact strips 12 and overload circuit breaker which may be reset 13, solenoid 6, contacts 18, and by the con f a di t tint, ducfor 21 to the main. The main line switch 1 Other objects of the invention will appear 10 is now energized to close its contacts 8 hereinafter, the novel combinations of eleand 9 which establishes a circuit to the 20 ments being pointed out in the annexed motor 70 and the releasing magnet'of the lai r brake 90, the shunt field being at the The drawing accompanying this specifisame time connected across the line. The cation illustratesdiagrammatically amotor' motor now starts to rotate, its speed being I controlling system embodying'iny invention. limited by the starting resistance 60 which 25 7 Referring to the drawing, I show a main is in series therewith The lever of the 80 line'switch 10 adapted when closed to commaster switch 20 is next moved over until plete a circuit to a motor 70 through a it assumes a position indicated by the [starting resistance 60. Thelatter is 'con broken line b and the magnet winding of trolled by themotor through an accelerating the fast speed switch 40 becomes energized, Y magnet 50 and contacts 1, 2, 3 and -l. The' its circuit being closed at the contact strip motor field is shown at 80 and an electro-- 14. The switch 40 now operates to close its magnetic brakeapparatus is shown at 90, contacts 5, thereby connecting the accelthe brake operating on a brake pulley secrating magnet 50 in a. circuit which is in cured to the shaft 5 of the motor. The fast parallel to the motor armature and a small 35 and slow speed magnet switch 40 controls a portion 'of the starting resistance 60. As circuit to the accelerating magnet 50 the motor is now running and generating a through the'normally open contact ,5. The coiinter-electro-inotive force, the acceleratmagnet switch 40 and the main line switch ing magnet 50 will operate its contacts 1, 2, 10 are both controlled by a master switch 3 and i in the order named, gradually, to 40 20. The overload relay is designated by 30. short circuit the resistance ()0 and permit 4 its full normal speed.

raise the core 1-7 and'open 55 tial fa will weaken the strength of the solenoid 6 to such a degree that it will not hold the switch 10. The resistance of the solenoid 16, however, is so high that the current in the magnet of the main line switch is re duced to such an amount that it no longer is able to maintain the switch in closed position and the latter drops its contacts thereby opening the motor and brake circuits and the motor comesto rest, the starting resistance 60 being reinserted into the armature 10 circuit, since the accelerating magnet is now open circuited at the contacts 9. It will he observed that the action of the overload relay 30 is very quick for the reason that at the instant that the coil 17 starts to separate the contacts 18, the coil 16 is placed in circuit and the further upward movement of the cores 1? and 17 is effected by the combined action of both coils working together and from this it follows that the 20 main line switclrlO will also operate quickly to dpen the motor circuit andstop the mo tor. As soon as the main line switch has operatedthe coil 15 is deprived of current but the winding 16 remains energized and 5 'is of sufficient power to retain the contacts 18 in open positiori. Under the present conditions the motor cannot be operated until the operator first moves the lever of the master switch back to its original or 03 position. As soon as he does that, the selfholding circuit of the overload relay magnet 16is broken at the contact 13 and the contacts 18 of the overload switch again come into contact with each other and the system assumes its normal position of rest as shown.

The overload relay 30 arranged according to my invention, will protect a motor or any other device in circuit therewith from excessive current flow, and it offers one great advantage over circuit breakers in general in that it contains no tripping devices 3 such as catches or triggers and furthermore may be reset ready for subsequent operation by merely centering the master switch,

which latter may be located at any convenient point or at any desired distance from the rest of the system.

While my-improved overload device will protect a motor or any other electrical device from an overload, it will be observed 'that the main line switch cannot maintain itself in closed position unless the pressure of "the mains is substantially of normal potential for it is apparent that any substanlling ofi in potential of 'Ithemain line switch closed and the main circuit will be interrupted at the contacts 8. Thus it is seen that my invention protects against abnormal low potential as well asfagainst excessive current flow, for in both cases the main circuit is opened. As soon as conditions have again become normal themam circuit may be closed and if said circuit 1ncludes a motor, the starting resistance will always be included in the circuit so that it is impossible to close the motor circuit at a time when the starting resistance is short circuited and thereby damage the motor.

For clearness of illustration, I'have shown and described the overload relay as compris: ing a plurality of cores and a magnet winding for each core,'but it is to be understood that a single core could just as well be used in place of the two cores as shown, and the high and low resistance coils 16 and 15 respectively, could be wound one upon the other similar to the primary and secondary windings of a transformer, the windings being arranged and connected so as to assist each other and not act in opposition.

What I claim and desire to have protected by Letters Patent of the United States is 1. The combination with a main line switch, an electromagnet for moving said switch to closed position, a relay having manually closed contacts in a circuit of said electromagnet, a magnet winding for said relay arranged to effect the operation of the same upon an overload, an additional magnet winding for the relay, normally short circuited by the relay contacts and adapted to assist in the operation of the relay upon the initial separation of the relay contacts, and a manual switch controllinga circuit through said additional magnet winding and the winding of the main line switch in series.

2. The combination with a main line switch, of an electromagnet for moving said switch to closed position, an overload relay having a low" resistance winding in series with the main line switch contacts and a high resistance winding in series with the magnet winding of the said main line switch,

a short circuit around said high resistance relay winding normally established by the relay'contacts, and a hand switch controlling a circuit to the magnet windingof the main line switch in series with the contactsof the overload relay.

3. The combination with a main line switch, of an electromagnet for moving said switch to closed position, an overload relay having'a low resistance Winding in series with the main line'switch contacts and a.

magnet winding of the said main Tline switch, a short circuit around said high resistance relay winding normally established by the relay contacts, a switch controlling a circuit tothe magnet of the main line switch and thereby energize thelow resistance winding of the relaymeans' operated by the relay upon an overl circuit around thelhigh resistance'winding of the relay and thereby eflectgthe opening of the main line switch. r v r A. The combination with a main line 3'30- high resistance winding in series with the cad opening the short AVAILABLE Cap? 1 m m a switch, of an electromagnet for moving said switch to closedposition, an overload relay having a seriesand shunt winding adaptedto act cumulative, means operative upon an overload for placing said shunt winding and the magnet of the main line switch in series to effect the opening of the main line I switch, and a hand switch controlling the ci 'cuit through the main line switch magnet. 55. The combination with a main line switch, of a magnet for closing said switch, an overload relay controlling the opening of said switch, a magnet winding associated 

